A sealing system is usually applied in a conduit which is itself incorporated in a construction element that divides, for instance, two compartments. A pipe or cable may extend through the conduit from one of the two compartments into the other. Such a conduit is often present on board of vessels and/or other offshore applications such as oil rigs. These conduits are often referred to as pipe or cable penetrations or transit systems. These penetrations are seen as unwelcome necessities in such a construction. Pipes for, for instance, water distribution and water wastage systems, air conditioning systems, hydraulic and pneumatic control, sprinkler etc. but also for transport of gas, or oil, need to be extending throughout such a construction, even though this entails introducing “weak spots” in a separation of the compartments. Cables could be electricity cables.
Such weak spots do not manifest themselves to a great extent in the mechanical strength of the construction but much more in the undesired transport of physical phenomena throughout the structure. One of these physical phenomena is the occasion of a fire which needs to be confined to only one area as long as possible, not only to allow for control and extinguishing the fire, but also to provide time for people present in compartments near to the fire for reaching a safe distance from the fire before it further extends. To prevent smoke and/or fire from passing through the conduit from one compartment to another, the conduit is usually provided with material that closes the conduit, at least for some time, when the conduit is exposed to heat due to a fire.
Although above reference is made to a construction element having a conduit and dividing two compartments, it is also possible that the construction element separates a compartment from the surrounding environment. It is thus possible that one side of the construction element is exposed to atmospheric conditions.
It will be appreciated that a pipe extending through a conduit, the conduit itself and the construction element into which the conduit is incorporated, are each usually made of a heat conducting material, for instance aluminium or steel. It is often the case that in these circumstances, heat still only enters the conduit sleeve via the pipe or pipes which extend from the side exposed to fire into the conduit. This is because entrance of heat through material of which the conduit is made, is often inhibited by a thermally insulating lining provided against the outer wall of the conduit and the construction element in which the conduit is incorporated.
However, nowadays, thermally insulating lining is not always applied around the conduit and consequently heat can be conducted through the conduit material from an outside to an inside side of the conduit. It follows that heat can be supplied via at least two routes to the inner space of the conduit. The first route is the supply via the pipes extending into the conduit and a second route is the supply of heat to the inner space of the conduit by the thermally conductive material out of which the conduit is made. As heat may be supplied via two routes, heat may be supplied very rapidly to the inner space of the conduit sleeve. These conditions are frequently found in offshore constructions and vessels, where construction materials are indeed made of metal, i.e. a heat conducting material. In constructions other than offshore constructions and vessels, like for instance onshore constructions, entrance of heat via the second route takes place much less often, if occurring at all.
WO 2006/097290 describes a system which is to a certain extent suitable for placement in a conduit as described as above. That system comprises heat expandable rubber sleeves. The rubber is made heat expandable by incorporation of heat-expandable graphite into that rubber. The system further comprises a fire resistant and/or watertight sealant for sealing off both ends of the conduit. When exposed to a nearby fire, the heat transferred into the conduit causes the expandable sleeves to expand and as such to seal off the conduit by forming a soft, almost powder-like mass without offering mechanical stability to the sealing. The expansion may cause the sealant layer to break. This breaking is in itself not a problem as the expanded sleeves have sealed off the conduit before the sealant layer breaks. Sometimes, also the sealant is made heat-expandable.
To allow for rapid and uninhibited thermal expansion, the components of the rubber sleeves are kept together within the dimensions of the sleeve but are certainly not captured in a rigid internal structure. Consequently, the sleeves are rather soft. As one never knows how much heat input is provided to the sealing system, and to ensure that it responds timely and sufficiently the system is such that even when only a relatively small increase in temperature is experienced a portion of the system expands, and closure of the conduit takes place. In other words, due to the uncertainty in the amount of heat reaching the sealing system, the system is made very sensitive. An “excess” of heat results consequently in an overresponding expansion, even outwards the conduit.
Although such systems are satisfactorily used and pass many fire safety tests, an alternative and perhaps an even further improved system, remains desirable, as safety on board of offshore constructions and/or vessels is in practice always a compromise between costs and time during which a penetration has to withstand a fire at one side of the penetration.
It is an object of the invention to provide an alternative, and for certain circumstances more suitable system.